Motor regulation.



EK f3.. WRIGH.

MUYOR REGULATION.

Mmc/mora min Aucmzs, :1911.

milie@ Mar, 7,1916.

MTOE REGULEIPN.

Specification of Letters Patentes v, 1916.

Application filed August 28, i911. Serial No. 645,518.

' known that I, Ennns'r llfnrorrr, a cit en ci the United rita s, res ling at Norwood, in the county oi' Hamilton I and State of Ohio, have invented certain new and use-ful Improvements in Motor Regula? tion, of which the 'following is a full, clear, and exact specification,

My invention relates to motor regulation.

Then an induction motor is used to drive' a variable load, there are pronounced changes in speed oi? the motor in inverse sense to changes in the load.

.It is the object or my invention to provide system of regulation whereby an induction motor n'iay drive a variable load at a substantially constant hut adjustable speed.

In carrying' out my invention a smaller direct current machine is mounted on the shaft or" the induction motor or otherwise mechanically connected thereto. This direct current machine is connected to a direct current circuit` and h its field strength so adjusted that for a given load on the induction motor any speed for which s'uch motor is adjusted the direct current machine floats on the direct current circuit. Upon an :increase or decrease in the load there is a slight slowing down or speeding up of the moving parts, and this causes the direct current machine to act as a motor or as a generator respectively to counteract the tendency to slow down or speed up.

r)The various novel features of my invention will appear from the description and drawing, and will he particularly pointed out in the claims.

ine single ligure ot the drawing shows diagrammatically one embodiment of my in-v wise mechanically connected thereto, is a smaller direct-current machine 15, the armature of which is connected, through a switch 16, across a direct current circuit 17 of substantially constant voltage. In thel circuit or' the field winding 18 ot the direct current machine 15 is a rlieostat 19.

lVith the switch 16 open, the rheostat 13 is properly adjusted to obtain the desired speed of the rotating parts fora given load on the belt 1st; this given load will usually, though not necessarily, he the average load. Then the rheostat 19 is adjusted. to make the voltage oi the machine 15 substantially equal to that of the circuit 1'?. Upon closing the switch 16 the machine 1:3 now floats on the circuit 17, neither taking energy there from nor supplying energy thereto. Upon an increase in the load above the aforesaid given value, the moving parts slow down slightl,y whereupon the machine 15 taires energy iroin the circuit 17 and acts as motor to assist the motor to drive the variable load. Because of the assistance given bythe motor 15, the change in speed is but a small part of what it would otherwise he. Should the load decrease below such given value, the moving parts speed up slightly and the machine supplies energy to the circuit 17. This puts an increased load on the motor 10, Aand makes the speeding up consequent upon the diminution or the variable load but a fraction of what it would otherwise be. This action of themachine 15 as a motor or a generator according as the variable load transmitted through the belt 14 increases above or decreases lbelow the given value, not only maintains the speed of the moving parts substantially constant, lout also maintains the current taken bythe motor 10 from the circuit 11 substantially constant.

In order to obtain a higher or lower sul)- stantially constantv speed, the resistance of therheostat 13 is decreased or increased respectively, and the 'resistance of the rhecstat 19 is correspondingly decreased or increased respectively to make thev voltage of the machine 15 substantially equal to that of the circuit 17 for the speed esredi; Quite a wide range of speed isohtainalilc-- Various modifications mayfhomade in the precise arrangement shown and described, and I aim to cover-al1 such modifications llo.

i benennen an raient l VWliicli do not involve a departure from the vspirit and scope of my invention as set forth 'voltage thereof approximately equal to that u oi the direct current circuit when the induction motor 1s operating at any one of lts.

normal speeds. v

53. in combination, an induction motor .lrrving 'variable load, means for varying v, the resistance ot the secondary circuit of rent circuit across which said direct, current` and that the sai'd Letters earnJ Signed and said-motor to enable said motor tov drive the load at diilerent speeds belen7 synchronism, a direct current machine mechanically connected' to said induction motor, a direct curmachine is connected, and means for varynig the ctrornotive force or' said direct current n bine whereby tbe latter absorbs lluctuat ins in the load to main the speed ol' the ino-ter substantially constant at any of said lvalues below synchronism.

f 3. ln combination, an induction motor of the Wound rotor typel driving a v: riable load, a variable resistance in the rotor circuit of said motor to enable said motor to run diierent speeds, adirect current machine mechanically connected to said induction motor, a direct current circuit across which aid direct current machine is connected, and means or'varying the voltage of snidydirect current machine, said direct cui rent machine operating as a generator when the load is below normal value and operatas motor when the load is above normal value to .maintain the speed of the inlfluction motor substantially constant for a resistance in the rotor circurrent machine to render the said electro-` motive Jforce approximately equal to that of Asaid directl current circuit when said motor is operating at any one of its normal speeds. 5.111 combination, a. variable speed n1- duction motor, a variable load driven by said motor,lmeans for maintaining the speed of the motor at a substantially constant value below synchronous speed when once adjusted, said means comprising` a direct current machine mechanically connected to the motor shaft, and means for varying the electromotive .force of said direct current machine to render said machine edective to absorb fluctuations in the load on said motor for predetermined speed of said motor.

(l. ln combination, a variable speed motor, a variable load driven by said motor, a dynemo-electric machine capable of acting as a generator or motor mechanically connected to said first inotoran electrical circuit yacross which terminals of said dynamo-electric machine are connected, and means operative to vary the electromotive force developed by saididynaino-electric machine due to its ac' tion asa generator to enable said machine to substantially absorb fluctuations in the load on said first motor when'the latter is operating at any of its predetermined speeds.

Milwaukee, Wis., Aug. 8, 19M/,1f

ln testimony whereof I ailifmy signature, in the presence of two Witnesses.

ERNEST A. WRIGHT.

Witnesses:

. G. M. Hin'rfr, H. DnTWILnR.

lt is hereby certified that in Letters Ritent No.l1,174,373,1granted Maronti,

ment in nl'otor Regulation, an error appears in the printed-sfr' ma conform to tf- 235i day of March, A. D., 1916.

i916, upon the application of Ernest A. Wright, of Norwood, (Ehio, for an improveism-agen requiring Patent should be read withl this correction therein- ,that-.'

ecord ci the case in the Patent G'liicety` 

